Evaluation method based non-invasive imaging in Parkinson’s disease models

Yiseul Choi,Eun Sang Lee,Jang Woo Park,Youn Kyoung Jeong,Mijeong Park,Hye Kyung Chung 한국실험동물학회 2021 한국실험동물학회 학술발표대회 논문집 Vol.2021 No.7

Parkinson’s disease (PD) is the second most common neurodegenerative movement disorder and is characterized by the loss of dopaminergic neurons in the nigrostriatal system. To monitor the PD, PET with [18F]FP-CIT for the dopamine transporter (DAT) has become a widely used tool. For PD study, invaluable tools are neurotoxin-based animal models. To validate the usefulness of these animal models in DAT imaging, we discuss the evaluation of these models. To develop most classical neurotoxin PD animal models, we injected 6-hydroxydopamine (6-OHDA) into the substantia nigra of mouse or treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) by oral routes. After that, [18F]FP-CIT PET imaging were acquired. The changes in [18F]FP-CIT uptake were also analyzed using PMOD software. For analysis of 6-OHDA induced PD model, we used [18F]FP-CIT binding ratio observed in the right/left striatum of the mice. Ratio average of 6-OHDA induced group was 0.477 as compare with control group ratio average 0.987. When MPTP-induced PD model were analyzed by [18F]FP-CIT binding ratio in the average of left and right striatum with the cerebellum as a reference, MPTP-treated group was 1.944 compared to average of the control group ratio 2.924. In conclusion, the evaluation of each PD model with non-invasive imaging has shown to be a valuable objective of PD research. In the future, these analyzes to preclinical drug evaluation may be suitable for development of new treatment.

Synthesis of ZnO Nanorods/Carbon Nanofiber Composites Using Electrochemical Deposition for Efficient Supercapacitor Electrodes: Control of Nucleation and Growth of ZnO Nanorods

Park, Yiseul,Oh, Misol,Kim, Jae Hyun American Scientific Publishers 2016 Journal of Nanoscience and Nanotechnology Vol.16 No.11

<P>ZnO nanorods can be electrochemically deposited onto carbon nanofiber (CNF) substrates and used for high-performance supercapacitors. The conductive, three-dimensional structure of the CNF web allows for electrodeposition of the ZnO nanorods. Therefore, the properties of the CNF substrate, as well as the deposition conditions, directly relate to the deposition mechanisms of the ZnO nanorods. The ZnO nanorod structure can be modulated by tuning the current density, precursor concentration, and type of applied current. These parameters affect the nucleation and growth mechanisms, resulting in different structures of ZnO nanorods. Applying a pulsed current with a rest time (5 s) during electrodeposition produces denser and narrower ZnO nanorods than those prepared under a constant current. The additional ZnO thin film coating by atomic layer deposition (ALD) on the CNF substrate exhibits a different tendency of the deposition of ZnO nanorods by acting as a seed layer.</P>

(Photo)Electrochemical selective chloride oxidation

Yiseul Park(박이슬) 대한환경공학회 2022 대한환경공학회 학술발표논문집 Vol.2022 No.11

Organic dye-sensitized TiO₂ for the redox conversion of water pollutants under visible light

Park, Yiseul,Lee, Su-Hyun,Kang, Sang Ook,Choi, Wonyong Royal Society of Chemistry 2010 Chemical communications Vol.46 No.14

<P>Titania nanoparticles sensitized with metal-free organic dye exhibit high visible-light activities for the redox conversion of water pollutants in a wider pH range in comparison with TiO<SUB>2</SUB> sensitized with ruthenium bipyridyl complexes.</P> <P>Graphic Abstract</P><P>Titania nanoparticles sensitized with metal-free organic dye exhibit high visible-light activities for the redox conversion of water pollutants in a wider pH range in comparison with TiO<SUB>2</SUB> sensitized with ruthenium bipyridyl complexes. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b924829c'> </P>

Reverberation Mapping of PG 0934+013 with the Southern African Large Telescope

Park, Songyoun,Woo, Jong-Hak,Romero-Colmenero, Encarni,Crawford, Steven M.,Park, Dawoo,Cho, Hojin,Jeon, Yiseul,Choi, Changsu,Barth, Aaron J.,Pei, Liuyi,Hickox, Ryan C.,Sung, Hyun-Il,Im, Myungshin American Astronomical Society 2017 The Astrophysical journal Vol.847 No.2

<P>We present the variability and time-lag measurements of PG 0934+013 based on a photometric and spectroscopic monitoring campaign over a two year period. We obtained 46 epochs of data from the spectroscopic campaign, which was carried out using the Southern African Large Telescope with similar to 1 week cadence over two sets of four month-long observing period, while we obtained 80 epochs of B-band imaging data using a few 1 m class telescopes. Due to the seven month gap between the two observing periods, we separately measured the time lags of broad emission lines, including H beta, by comparing the emission line light curve with the B-band continuum light curve using the cross-correlation function techniques. We determined the H beta lag, tau(cent) = 8.46(-2.14)(+2.08) days in the observed frame based on Year 2 data, while the time lag from Year 1 data was not reliably determined. Using the rms spectrum of Year 2 data, we measured the H beta line dispersion sigma(line) = 668 +/- 44 km s(-1) after correcting for the spectral resolution. Adopting a virial factor f = 4.47 from Woo et al. ( 2015), we determined the black hole mass M-BH = 3.13(-0.93)(+0.91)x10(6) M-circle dot, based on the H beta time lag and velocity.</P>

Exfoliated and reorganized graphite oxide on titania nanoparticles as an auxiliary co-catalyst for photocatalytic solar conversion

Park, Yiseul,Kang, Seung-Hee,Choi, Wonyong Royal Society of Chemistry 2011 Physical chemistry chemical physics Vol.13 No.20

<P>The hybrid of graphite oxide (GO)/TiO<SUB>2</SUB> was prepared through the spontaneous exfoliation of bulky graphite oxide and reorganization with TiO<SUB>2</SUB> nanoparticles as a solar conversion and hydrogen-generating photocatalyst. GO/TiO<SUB>2</SUB> showed enhanced activities for both photocurrent generation (in an electrode form) and hydrogen production (in a slurry form) than those of bare TiO<SUB>2</SUB> under UV light irradiation. The enhanced photocatalytic activity of GO/TiO<SUB>2</SUB> is ascribed to the ability of graphitic layers in accepting and transporting electrons from excited TiO<SUB>2</SUB>, promoting the charge separation. When GO was hybridized with platinized TiO<SUB>2</SUB> (Pt/TiO<SUB>2</SUB>), it showed a marked synergistic effect for the photocatalytic hydrogen production compared with GO/TiO<SUB>2</SUB> and Pt/TiO<SUB>2</SUB>. This indicates that the cheap and abundant carbon material can be a good candidate for an electron attracting reservoir and an auxiliary co-catalyst for the photocatalytic hydrogen production.</P> <P>Graphic Abstract</P><P>The hybrid of graphite oxide (GO)/TiO<SUB>2</SUB> was prepared through the spontaneous exfoliation of bulky graphite oxide and hybridization with TiO<SUB>2</SUB> nanoparticles, which showed markedly enhanced activities for both photocurrent generation and hydrogen production. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c1cp20697d'> </P>

Ambient-temperature catalytic degradation of aromatic compounds on iron oxide nanorods supported on carbon nanofiber sheet

Park, Yiseul,Kim, Chuhyung,Kim, Minsun,Kim, Soonhyun,Choi, Wonyong Elsevier BV 2019 Applied Catalysis B Vol.259 No.-

<P><B>Abstract</B></P> <P>Fe<SUB>2</SUB>O<SUB>3</SUB> nanorods loaded on carbon nanofiber sheet (Fe<SUB>2</SUB>O<SUB>3</SUB>/CNF) was found to be active in degrading aromatic pollutants spontaneously under the dark and ambient conditions without using any chemical reagent or external energy to assist the degradation reaction. The removal of aromatic pollutants was not caused by adsorption but by oxidative degradation since the generation of degradation intermediates and products was observed. The Fe<SUB>2</SUB>O<SUB>3</SUB>/CNF exhibited selective degradation activities for aromatic-compounds. Degradation was induced by Fe<SUB>2</SUB>O<SUB>3</SUB>/CNF only, whereas neither iron oxide nor bare CNF alone exhibited any degradation activity. The degradation on the Fe<SUB>2</SUB>O<SUB>3</SUB>/CNF was enabled only in the presence of dissolved O<SUB>2</SUB> of which reduction led to the generation of reactive oxygen species (ROS). It is proposed that electrons spontaneously transfer from aromatic-compound to O<SUB>2</SUB> viaFe<SUB>2</SUB>O<SUB>3</SUB>/CNF with initiating the oxidative degradation and the concurrent ROS generation. The direct electron transfer from organic compound to Fe<SUB>2</SUB>O<SUB>3</SUB>/CNF, which lead to oxidative degradation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Iron oxide/CNF spontaneously decomposes pollutants under dark and ambient conditions. </LI> <LI> Neither iron oxide nor CNF alone shows any degradation activity. </LI> <LI> Iron oxide/CNF exhibits selective degradation activities for aromatic compounds. </LI> <LI> Electron transfer from aromatic compounds to iron oxide/CNF causes ROS generation. </LI> <LI> Sheet form of catalyst is easily handled and recoverable. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

리튬이온커패시터용 Polyaniline/WO₃ 음극 제조 및 이의 광 조사에 따른 전기화학적 특성 변화

박이슬 ( Yiseul Park ) 한국화학공학회 2018 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.56 No.6

본 연구에서는 리튬이온커패시터의 음극으로 polyaniline (PANI)/WO₃ 전극을 제조하고, 이의 전기화학적 특성을 측정, 분석하였다. WO₃ 전극 표면에 PANI를 전기화학적으로 담지 하였을 때 PANI의 용량이 더해져 WO₃ 전극보다 충, 방전 용량이 향상되었다. 한편, 충, 방전 시 태양광을 조사하여 충, 방전 용량과 쿨롱 효율(coulombic efficiency)에 빛 조사가 미치는 영향을 파악하였다. WO₃ 전극과 PANI/WO₃ 전극에 태양광을 조사하였을 때, 두 전극의 충, 방전 용량과 쿨롱 효율은 태양광을 조사하지 않았을 때보다 증가하였다. 이는 WO₃가 빛 조사에 의해 광전자를 생성하여 전극의 전기화학적 특성에 영향을 주기 때문으로 해석되며, PANI/WO₃의 경우 PANI 또한 빛에 의해 여기 될 수 있어 전극의 특성이 변하게 된다. 빛 조사에 의해 추가로 생성된 광전자가 Li⁺ 이온의 삽입(intercalation)에 사용되어 용량을 증가시킬 수 있을 뿐 아니라, 전극의 전도성을 높여 쿨롱 효율을 향상 시키는 것으로 여겨진다. PANI/WO₃는 충, 방전을 반복하여 진행하게 되면 PANI의 불안정성으로 인해 용량이 점차 감소되게 되지만, 빛 조사 시에는 생성된 광전자와 정공으로 인한 산화-환원 반응에 의해 PANI의 안정성이 크게 향상되어 충, 방전 용량의 감소없이 안정적으로 유지되었다. In this study, polyaniline (PANI)/WO₃ electrode was prepared as an anode of a lithium ion capacitor, and its electrochemical characteristics were measured and analyzed. When PANI was electrochemically deposited on the surface of WO₃ electrode, the capacity of PANI/WO₃ was improved with increase of the deposited amounts of PANI. Furthermore, the effect of light irradiation on capacity and coulombic efficiency was examined by irradiating sunlight during charging and discharging. When the light was irradiated to the WO₃ electrode and the PANI/WO₃ electrode, those capacities and coulombic efficiencies were increased compared to that measured under the dark condition. It is attributed to the photocatalytic property of WO₃ that can generate photoelectrons by light irradiation. In PANI/WO₃ electrode, PANI also can be excited under the light irradiation with affecting the electrochemical property of electrode. The photoelectrons improve the capacity by participating in the intercalation of Li⁺ ions, and also improve the coulombic efficiency by facilitating electrons’ transport. Under the dark condition, the capacity of PANI/WO₃ was gradually reduced with increase of cycles due to a poor stability of PANI. However, the stability of PANI was significantly improved by the light irradiation, which is attributed to the oxidation-reduction reaction originated from the photogenerated electrons and holes in PANI/WO₃.

광전극 소재를 중심으로 본 광전기화학적 이산화탄소 전환기술 동향 분석

박이슬(Yiseul Park),최지나(Jina Choi) 한국에너지기후변화학회 2016 에너지기후변화학회지 Vol.11 No.1

This work is a short review of recent studies on photoelectrochemical reduction of carbon dioxide (CO₂). Photoelectrochemical reduction of CO₂ is a light-driven CO₂ reduction, which harnesses solar energy to convert CO₂ into higher-energy products (e.g., liquid fuels). Studies on photoelectrochemical cell have mainly focused on photoelectrochemical H₂ production via water splitting, but, recently, photoelectrochemical reduction of CO₂ have been actively investigated as a part of the artificial photosynthesis studies. In this short review, the recent literature on photoelectrochemical reductions of CO₂ is reviewed. Various photoanode and photocathode materials are compared and different approaches to enhancing solar-to-fuel efficiency and selectivity of target product are described.

효율적인 광전기화학적 물 분해 및 이산화탄소 환원을 위한 산화 전극 개발

박이슬(Yiseul Park) 한국에너지기후변화학회 2019 한국에너지기후변화학회 학술대회 Vol.2019 No.05